<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    body {
      height: 100vh;
    }
    .box1{
      background-color: red;
      /* display: none; */
      visibility: hidden;
      height: 0;
    }

    .box2{
      background-color: yellow;
    }

    .box3{
      background-color: green;
    }
  </style>
</head>

<body>
  <div class="box1">box1</div>
  <div class="box2">box2</div>
  <div class="box3">box3</div>
  <script>
    // let b = [1, 2, 3, 4, 5, 6, 7, 8, 9]
    // console.log('a=', b.length / 3);
    // console.log('a=', b.length % 3);
    // let l = b.length / 3
    // let j = 0
    // for (let i = 0; i < b.length; i++) {
    //   console.log(b[j],b[j+1],b[j+2]);
    //   j+=3
    // }

    const directionEnum = new Map()
    directionEnum.set(1, '东')
    directionEnum.set(2, '西')
    directionEnum.set(3, '南')
    directionEnum.set(4, '北')
    directionEnum.set(5, '辅东')
    directionEnum.set(6, '辅西')
    directionEnum.set(7, '辅南')
    directionEnum.set(8, '辅北')

    console.log([...directionEnum]);

  </script>
</body>

</html>